import { MipmapGenerator } from './mipmapGenerator';
 
export class AsyncMipmapGenerator {
    private worker: Worker;
    private promise: Promise<MipmapGenerator>;
    private resolve!: (value: MipmapGenerator) => void;
 
    constructor(imageData: Uint8ClampedArray, width: number, height: number) {
        const workerCode = `
            self.onmessage = (e) => {
                const { imageData, width, height } = e.data;
                const levels = [];
                const sizes = [];
                
                // 模拟Mipmap生成过程
                let currentData = new Uint8ClampedArray(imageData);
                let currentWidth = width;
                let currentHeight = height;
                
                while (currentWidth > 1 || currentHeight > 1) {
                    const nextWidth = Math.max(1, Math.floor(currentWidth / 2));
                    const nextHeight = Math.max(1, Math.floor(currentHeight / 2));
                    const nextData = new Uint8ClampedArray(nextWidth * nextHeight * 4);
                    
                    // 这里应该调用实际的双线性过滤算法
                    // 为简化示例，使用原始数据
                    levels.push(currentData);
                    sizes.push([currentWidth, currentHeight]);
                    
                    currentData = nextData;
                    currentWidth = nextWidth;
                    currentHeight = nextHeight;
                }
                
                levels.push(currentData);
                sizes.push([currentWidth, currentHeight]);
                
                self.postMessage({
                    type: 'complete',
                    levels,
                    sizes
                }, [levels.map(l => l.buffer), sizes]);
            };
        `;
 
        const blob = new Blob([workerCode], { type: 'application/javascript' });
        const workerUrl = URL.createObjectURL(blob);
        this.worker = new Worker(workerUrl);
 
        this.promise = new Promise((resolve) => {
            this.resolve = resolve;
            this.worker.postMessage({
                imageData,
                width,
                height
            }, [imageData.buffer]);
        });
 
        this.worker.onmessage = (e) => {
            if (e.data.type === 'complete') {
                const generator = new MipmapGenerator(
                    new Uint8ClampedArray(0), 0, 0
                );
                generator.mipLevels = e.data.levels;
                generator.mipSizes = e.data.sizes;
                this.resolve(generator);
                URL.revokeObjectURL(workerUrl);
            }
        };
    }
 
    public generate(): Promise<MipmapGenerator> {
        return this.promise;
    }
}